1. Field of the Invention
The present invention relates to an electrical connector for electrically connecting an electronic package such as a central processing unit (CPU) with a circuit substrate such as a printed circuit board (PCB), and particularly to a land grid array (LGA) connector assembly having a loading system for protecting the connector assembly from deformation or warpage.
2. Description of Prior Art
An integrated circuit (IC) package having leads arranged in a land grid array (LGA) is known as an LGA package. LGA packages have relatively low height, which saves valuable space in electronic assemblies.
Connectors for removably mounting an LGA package on a PCB are known as LGA connectors. An LGA connector combined with ball grid array (BGA) technology typically comprises a thin and substantially flat insulative housing which is positioned between the LGA package and the PCB. The housing defines an array of passageways receiving electrical terminals therein. The terminals correspond with the array of leads of the LGA package. Each terminal has a pair of opposite free ends that project beyond opposite top and bottom external surfaces of the housing. Prior to mounting of the LGA package on the PCB, the free ends are spaced apart a predetermined distance. The free ends are respectively engaged with corresponding contact pads on a bottom surface of the LGA package, and soldered to contact pads on a mounting surface of the PCB.
FIG. 7 shows a conventional LGA connector 9 for electrically connecting an LGA package 8 with a PCB (not shown). The connector 9 comprises a housing 91, and a fastening device assembled with the housing 91. The housing 91 has a plurality of passageways (not shown) with a plurality of conductive terminals (not shown) received therein. The fastening device comprises a metal clip 93 and a lever 92 mounted on opposite sides of the housing 91 respectively. The metal clip 93 comprises a pair of locating portions 932, a pair of opposite lateral pressing arms 931, and a driving hook 933 at a free end thereof generally between distal ends of the pressing arms 931. Each locating portion 932 is movably received in a groove 912 of the housing 91. Each pressing arm 931 is bent slightly downwardly at a middle portion 934 thereof. The lever 92 comprises a pair of acting portions 923, a driving portion 922 disposed between and offset from the acting portions 923, and a handle portion 921 bent perpendicularly from a distal end of one of the acting portions 923. Each acting portion 923 is secured in a lock 913 of the housing 91.
In use, the clip 93 is firstly rotated to be perpendicular to the housing 91. The handle portion 921 of the lever 92 is horizontal, and the driving portion 922 is at a highest position. The LGA package 8 is attached on the housing 91. The clip 93 is rotated down to a horizontal position, with the pressing arms 931 abutting against the LGA package 8. The handle portion 921 of the lever 92 is rotated upwardly to be perpendicular to the housing 91, and the driving portion 922 of the lever 92 is received in the driving hook 933 of the clip 93. The handle portion 921 of the lever 92 is rotated down toward the clip 93, and the driving hook 933 is driven downwardly until the clip 93 is in a final pressing position, with the pressing arms 931 firmly pressing the LGA package 8 on the housing 91.
At the final pressing position, the middle portions 934 of the pressing arms 931 apply downward forces on middle portions (not labeled) of the housing 91. The housing 91 at the grooves 912 applies downward forces on the locating portions 932 of the clip 93, thereby locating the locating portions 932 in the grooves 912. The locating portions 932 apply upward counterforces on the housing 91 at the grooves 912. The acting portions 923 of the lever 92 are secured in the locks 913 of the housing 91, with the locks 913 of the housing 91 applying downward forces on the acting portions 923. The acting portions 923 apply upward counterforces on the locks 913 of the housing 91.
Because the housing 91 has a plurality of passageways, a main body of the housing 91 is relatively weak. The housing 91 is subjected to the above-described downward forces acting on the middle portions thereof, and the above-described upward forces acting on two opposite end portions (not labeled) thereof. The opposite ends of the housing 91 are thus prone to warp upwardly and deform the housing 91. When this happens, the clip 93 cannot firmly press the LGA package 8. Therefore, the electrical connection between the conductive terminals of the connector 9 and conductive pads (not shown) of the LGA package 8 may be unstable or even lost.
In view of the above, a new land grid array connector assembly that overcomes the above-mentioned disadvantages is desired.